Buy and play Spartan Assault and you'll unlock exclusive bonus content in the Halo 4 Champions Bundle or Halo 4 Bullseye Pack, which are both out on 20th August. The bonus content includes a new weapon skin, two armour skins and a Spartan stance.

On Windows Phone 8, 1GB RAM is required. A Windows Phone 8 version supporting 512MB RAM will be released in August 2013.

Meanwhile, Microsoft has released the first part of a digital interactive graphic novel inspired by Xbox One exclusive Ryse. It's called Ryse: Sword of Damocles, and it lets you unlock collectibles for use in the Xbox One game after it launches. These unlocks grant "an early leg up in the multiplayer aspect of the game", Microsoft said.